1. Field of the Invention
This invention relates to photographic apparatus of the single lens reflex type having an objective and a finder for observing an image formed with light passing through the objective.
2. Description of the Prior Art
In the art of 35 mm single lens reflex cameras, it has been the common practice that a reflex mirror is used in between the objective and the film plane to take a finder-image forming light beam out of the light from the objective, by which the finder image on the focusing screen is formed to the same magnification to that of the image to be formed on the film plane, and a pentagonal roof type prism is used for laterally inverting the finder image so that a correct image can be observed through the eyepiece.
Recent efforts at a further minimization of the sizes of photographic lenses have made considerable progress, but the sizes of the reflex mirror and the focusing screen, because the size of area of one frame of film is constant, appears substantially impossible to reduce. The pentagonal roof type prism also, because its having a large volume in itself owing to the geometrical configuration and because the sizes of all its faces are dependent on the size of the focusing screen, is very difficult to reduce in size. These parts thus give an obstacle to progress in minimizing the size of the entire body of the camera system.